Rhythm generating circuit for musical instrument



June 31), 1970 J, PLUNKETT 3518 352 RHYTHM GENERATING CIRCUIT FOR MUSICAL INSTRUMENT Filed June 30, 1967 5 Sheetsheet 1 CLOCK RING COUNTER OSCILLATOR I 2 3 4 '0 H o 64 p43 RESISTOR MATRIX CHOPPER SWITCH BANK PERCUSSION- GENERATOR DOWN MODULATOR BEAT EMPHASIS FIG. I. AMPLIFIER INVENTOR.

BRADLEY J. PLUN KETT Q/QM ATTORNEY Jum 1970, v a. J'QPLUNKETT 3,

RHYTHM GENERATING CIRCUIT FOR MUSICAL INSTRUMENT Filed June 50 1967 3 Sheets-Sheet 2 CLOCK OSCILLATOR H6 2.

SWITCH BANK PERCUSSION GEN ERATOR INVENTOR.

BRADLEY J. PLUNKETT ATTORNEY June 30, 1970 RHYTHM GENERATING CIRCUIT FOR MUSICAL INSTRUMENT Filed June 50. 1967 RHYTHM GENERATOR CLOCK OSCILLATOR II STAGE "0" STAGE I STAGE 2 STAGE 3 STAGE 4 STAGE 5 STAGE 6 STAGE 7 STAGE 8 STAGE 9" OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT STAGE IO" OUTPUT STAGE II OUTPUT COLLECTOR OF FIRST FLIP FLOP CIRCUIT (In PASS) COLLECTOR OF SECOND FLIP FLOP CIRCUIT 2m) MANUAL DRIVER PEDAL DRIVER OUTPUT VIENNESE MANUAL DRIVER OUTPUT WALTZ P EDAL H P D RIVER OUTPUT FIG.

8. J. PLUNKETT 3 Sheets-Sheet S In PASS 2N0 PASS OI23456789IOIIOI234567891011 INVENTOR.

BRADLEY J. PLUNKETT E /mm ATTORNEY United States Patent O 3,518,352 RHYTHM GENERATING CIRCUIT FOR MUSICAL INSTRUMENT Bradley J. Plunkett, Sepulveda, Califl, assignor to Warwick Electronics Inc., Chicago, Ill., a corporation of Delaware Filed June 30, 1967, Ser. No. 650,530 Int. Cl. Gf 1/00; G10h 1/02 U.S. Cl. 84-1.03 5 Claims ABSTRACT OF THE DISCLOSURE A rhythm generating circuit comprises a clock oscillator driving a ring counter, the output of which is fed to a distribution matrix and thence to a bank of switches. The switches, individually, when operated, establish predetermined rhythm patterns, as for example preselected dance rhythms. Output from the switch bank serves to activate audio frequency sources, either through a modulator or by direct stimulation of the audio frequency. Emphasis means are provided for giving increased. amplitude on each downbeat, i.e. on the first beat of each measure. Means are also provided for chopping or curtailing the beat, so that where a particular rhythm calls for rapidly recurring beats, they will be separated by an appreciable time interval.

BACKGROUND OF THE INVENTION It is known in the art to provide rhythm circuits having a clock oscillator which drives a ring counter, the output of which actuates various percussion tone simulators at preselected rhythm patterns. These rhythm patterns then constitute the envelopes for the percussion sounds, which are applied repetitively to the amplifier and speaker of the musical system.

SUMMARY OF THE INVENTION The present invention constitutes an improvement over the above described rhythm circuits, in the inclusion of certain circuits which provide emphasis of increased amplitude of the initial beat in each measure, thereby giving downbeat emphasis. Also, certain rhythms, particularly dance rhythms, call for beats which occur very close together. The beat signals generated by the ring counter normally occur one upon the other with minimal spacing between the two. Thus, if two contiguous beats are required, there is not enough separation to be distinguishable. The present invention provides a chopper or curtailing means which in effect shortens each output wave form of the ring counter, so that the beat pulses no longer run together but are separated by a measurable time interval. This makes possible the sounding of rhythms which require at certain points a very short interval between beats.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram illustrating the present invention.

FIG. 2 is a circuit diagram illustrating the circuit contents of one of the blocks constituting one of the improve- 'ments of the present invention.

FIG. 3 is a circuit diagram illustrating the contents of another block constituting a portion of the present invention.

FIG. 4 are synchronizedwave forms of useful in understanding operation of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, 11 designates a clock oscillator which delivers repetitive, measured negative pulses to a ring counter 12 having twelve output terminals 13, numbered 1 through 11 and 0 as shown. In operation of the circuit, at any given moment there will be a signal in the form of a positive voltage on one and only one of the terminals 13. Upon receipt of the next pulse from the clock oscillator 11 the next succeeding terminal 13 will go positive, so that a ring of positive square wave signals is constantly and successively applied around the terminals 13. This is illustrated in FIG. 4, wherein 14 represents the clock or triggering impulses applied by the oscillator 11 to the ring counter 12. The positive going pulse 16 represents the output at terminal or stage zero; 17 represents the output at stage 1; and so on through and around the entire set of terminals 13.

The pulses 16, 17 serve to activate or enable passage of audio frequency signals to a loudspeaker 18 through an output amplifier 19 from a suitable audio frequency source. This source may be either one of musical tones of predetermined pitch, represented by the tone source 21, or may be one or more specially generated percussive sounds represented by the source 22. For purposes of initial illustration attention will be focused on the tone sources represented by 21. Output from the ring counter 12 is selectively coupled to the tone sources 21 to rhythmically activate the sounding of such tone sources through the speaker 18. This coupling means consists of a resistive distribution matrix 25, a switch bank 23, a pulse amplifier 24 and a modulating circuit 26. For all or certain of the rhythms, the coupling circuit may also include a chopper or curtailing means 27, driven directly from the clock oscillator 11.

As is known in the art, actuation of one of the switches in the switch bank 23 will select through the matrix 25, predetermined ring counter pulses 16, 17 and apply them through the amplifier 24 to the modulator 26, where they serve to selectively pass tones from 21 to the speaker 18 at the rhythm determined by the switch selection in 23.

For simplicitys sake only one form of tone source 21 has been illustrated, being for example, the tone sources representative of a manual keyboard on an electronic organ. In actual practice it is customary to provide both pedal and manual keyboard tone sources, and to provide from the output of the switch bank 23 also selected pulses which actuate a pedal tone modulator corresponding to the manual modulator 26. It is in such a context that FIG. 4 illustrates the pulse pattern.

By way of example, when the Waltz switch is actuated in the switch bank 23, the zero beat or pulse 16 will be applied to the pedal modulator in the form of the pulse 16a. The number 4 beat or pulse 31 will be applied to the manual modulator 26 in the form of pulse 31a. The number 8 beat or pulse 32 will also be applied to the modulator 26 in the form of the pulse 32a. There will thus be provided a waltz beat rhythm in which the first beat is rendered through the pedal tones while the second and third beats are rendered through the manual tones.

A similar pattern is provided on the second phase or pass of each cycle of the ring counter 12 in the form of pulses 16b, 31b, and 3211. Each cycle of the ring counter consists of two stages or passes, the differenttial being achieved by a flip-flop circuit (not shown) interposed at the output of the switch bank 23 and creating the two gate signals shown at 33 and 34 respectively. These flip flops form no part of the present invention and serve simply to allow the twelve position ring counter 12 to create effectively twenty-four rather than twelve different beats. It has been found in practice that from these twenty-four different beats all desired rhythm patterns can be created, even such complicated dances as bolero and tango.

When operation of this present rhythm circuit is not desired, the moduator 26 may be turned on constantly by suitable switching (not shown). In this case it is preferred to incorporate some attenuation, for instance 6 db down, because the steady tones from the tone sources 21 sound louder to the ear than do the intermittent rhythmic tones when the modulator 26 is pulsed from the ring counter 12. Thus, it is desirable to increase the volume slightly when the rhythm circuit is placed in operation.

Chopper It will be noted that the pulse 16 and 17 occur contiguously in time without substantial quiescent period between them. Thus, if a particular rhythm calls for two such contiguous signals, there is no appreciable break between the two, and hence no discernible separation between the beats. This is illustrated for example at 36 in FIG. 4, Where beat No. 3 (pulse 37) and the contiguously occurring beat No. 4 (pulse 31) are both employed. To separate these beats, means are provided in accordance with the present invention for chopping or curtailing the outputs from the ring counter 12, so that there is appreciable time duration between termination of one modulating pulse and the onset of the other. This is illustrated at 38 where only the first portion of the pulse 37 is allowed to pass to the modulator 26. Thus when the Viennese Waltz switch is actuated in the switch bank 23, all pulses are curtained as shown by the chopped duration of pulses 38 and 39.

This chopping is achieved at 27, where the output appearing on terminal 41 of the switch bank 23 is killed or diverted, as shown schematically by the grounding switch 42, except when the clock oscillator pulses 14 are applied through the line or connection 43 from the oscillator 11 directly to the chopper 27. The chopper is placed in this condition of operation, as noted, by the closing of the Viennese Waltz switch in the switch bank 23, which closing is sensed by a connection denominated 44 in FIG. 1. While it would be possible to curtail the pulses of all the rhythms by this placing them under the concurrent control of the switch bank output 41 and clock oscillator 11, it is preferred to limit this operation only to those selected rhythms which require it.

The circuitry involved in the chopper 27 is shown in FIG. 2, where the grounding described hel'einbefore is actually accomplished by passing the rhythm pulses from the terminal 41 to a B- connection 51 through a transistor 42, which is rendered either substantially open circuit (high impedance) or substantially short circuit (low impedance) by the application of control voltage to its base 52.

Referring to FIG. 2, the terminal 43 is connected to the clock oscillator 11 and has residing thereon a positive voltage, for example, +105 volts, except during those relatively short periods (approximately 30 milliseconds), when the pulses 14 are being delivered by the clock oscillator 11. This positive voltage on the base 52 renders the transistor 42 conductive, so that point 41 during this condition is effectively tied to the B- terminal 51 and substantially bypasses the ring counter pu ses 16, 17 away from the pulse amplifier 24. Under these circumstances no modulation is applied to 26, and tone does not sound in the speaker 18 except during those regular 30 millisecond periods when the transistor 42 is in effect gated off by the receipt of clock pulses 14. Even then of course modulation pulses pass to 24 only in accordance with the selected rhythms delivered from the switch bank 23, for it is only then that there is output on 41 to be applied to 24. Under these circumstances the selecter rhythm pulses pass in their rhythmic pattern to the amplifier 24, but are shortened or curtailed from their normal duration, for example 50 to 500 milliseconds as shown at 16, down to approximately 30 milliseconds as shown at 14.

When the curtailing action is not desired, the terminal 44 is connected to B- through auxiliary switching in the switch bank 23, operated in conjunction with those preselected rhythms which require curtailing. Thus, unless such a preselted rhythm switch is operated, e.g. Viennese Waltz, Tango, Bolero, the base 52 is held at B potential, steadily gating the transistor to ofl. or high impedance condition and creating no chopping of the normal ring counter output appearing at 41. The se lected rhythm switches may be connected in series, so that when anly one of them is actuated, the connection from terminal 44 to B is broken, thereby rendering 42 conductive and applying B to terminal 41, except during those intervals when the clock pulses 14 are actually extant on the terminal 43.

Downbeat emphasis As noted, the present invention also contemplates a means for giving added emphasis to the down or zero beat in each measure.

Such downbeat emphasis may be applied to the musical tone sources 21, but for purposes of illustration will be shown as being applied to the special percussion tones generated at 22. Referring to FIG. 1 the ring counter output pulses 16, 17 after amplification in 24 are routed to the percussion generators 22 through the channel shown at 61, where they serve to activate the percussion tone generator. The output of the generators is then applied to the speaker 18 through an attenuating circuit 62. The attenuating circuit is controlled by a downbeat emphasis circuit 63 which in turn is controled from terminals numbered 11, 0 and 1 of the ring counter 12, through or gates 64- represented by diodes as shown. The attenuating circuit 62 includes a resistor 66 which is paralleled by a variable resistor 67 in the circuit 63, the magnitude of which is controlled from the ring counter 12. When there is an output signal on terminals 11, t), or 1, the resistance of 67 is lowered appreciably, thereby lowering the series impedance interposed between the generators 22 and the loudspeaker 18, and thus increasing the amplitude of said signals for the duration of those particular beats (11, 0, and 1).

The circuit of the downbeat emphasis 63 is shown in FIG. 3 where output from the tone generators 22 is applied through conductor 68, through the fixed resistor 66, and thence to the line 69 and to the output circuit 19, 18. The resistor 66, as noted hereinbefore, is paralleled by a variable resistor 67, in this case a light dependent resistor or LDR, the amplitude of which varies greatly depending upon the amount of light falling thereon from an incandescent light source 71. When the light 71 is dark, the resistance 67 is relatively high. When the light source 71 is energized, the light therefrom renders 6 7 relatively low.

Signal from the selected ring counter terminals is applied through the line 72 to the base of a transistor 73, rendering it conductive, and causing the light 71 to be energized from a power source 74. When there is no signal on 72, transistor 73 is non-conductive, cutting current in 71 down to a bare minimum and in effect darkening the LDR 67.

The light source, 71 being incandescent, does not respond instantaneously. Therefore it has been found desirable to turn its energizing circuit on, one beat ahead of the downbeat, i.e. terminal No. 11, and to keep it on for one beat after the downbeat, i.e. terminal N0. 1. This gives the actual downbeat pulse 16 its added emphasis through the circuit 62 for its entire duration and precludes shading it at either end.

When the downbeat emphasis is not desired, the LDR 67 is simply shorted by the closing of switch 81 located at any convenient point on the organ console.

Whereas the present invention has been shown and described herein in what is conceived to be the best mode contemplated it is recognized that departures may be made therefrom within the scope of the invention which is therefore not to be limited to the details disclosed herein but is to be afforded the full scope of the invention as hereinafter claimed.

What is claimed is: 1. A rhythm generating circuit fora musical instrument comprising:

counter means having a plurality of terminals for successively producing on said terminals a repetitive succession of activating signals,

at least one audio frequency source,

speaker means,

coupling means for selectively coupling said terminals to said source for effecting the sounding of said source through said speaker, at selected rhythms,

characterized by:

emphasis means coupled to at least one given said terminal for increasing the sounding amplitude through said speaker during the time when activating signal resides on said given terminal.

2. Circuit in accordance with claim 1, wherein:

said emphasis means includes,

variable impedance means interposed between said source and said speaker, and

means for lowering the impedance of said impedance means during said time.

3. A rhythm generating circuit for a musical instrument comprising:

counter means having a plurality of terminals for successively producing on said terminals a repetitive succession of activating signals,

at least one audio frequency source,

speaker means,

coupling means for selectively coupling said terminals to said source for eflecting the sounding of said source through said speaker, at selected rhythms,

characterized 'by:

curtailing means for shortening the duration of certain of said signals in response to certain predetermined selections in said coupling means.

4. Circuit in accordance with claim 3 wherein:

said curtailing means comprise by-pass means for bypassing audio frequency sound signals away from said speaker means and including variable impedance means capable of being varied from a very high impedance to a relatively low impedance, said impedance means being in its relatively low impedance condition, except 'when influenced by external control means,

first control means for intermittently placing said impedance means at its high impedance condition, for the said shortened durations,

second control means for continuously placing said impedance means in its high impedance condition,

and means for disabling said second control means in response to said predetermined selections.

5. A rhythm generating circuit for a musical instrument comprising:

counter means having a plurality of terminals for successively producing on said terminals a repetitive succession of activating signals,

at least one audio frequency source,

speaker means,

coupling means for selectively coupling said terminals to said source for effecting the sounding of said source through said speaker, at selected rhythms,

characterized by:

clock means for triggering said counter means to produce the successive said actuating signals,

curtailing means in said coupling means for shortening the duration of signals applied to said speaker, in response to direct activation from said clock means.

References Cited UNITED STATES PATENTS 3,247,307 4/1966 Campbell 84-1.03 3,255,292 6/1966 Park 841.03 3,286,013 11/1966 Brand et a1. 841.25 3,358,068 12/1967 Campbell 841.01

WARREN E. RAY, Primary Examiner U.S. Cl. X.R. 84l.18, 1.24 

